Recent terrorist activity has underscored the relative lack of protection afforded to the general population from weapons of mass destruction. Occupants of buildings are especially vulnerable to airborne contaminants such as highly toxic chemical agents possibly used in terrorist attacks or toxic chemical accidents. These highly infectious chemical or biological agents can be used by terrorists or in weapons of mass destruction. The harmful agents are transmitted through the air in an effort to harm those within its path.
Although military systems exist which can protect individual soldiers in the field from these types of weapons, they have the disadvantage of high costs. Another disadvantage is the severe degradation in the ability of individuals to perform even the simplest tasks.
The military has also developed collective protection devices for creating relatively small protected areas. This is accomplished through the use of inflatable field hospitals and vehicle interiors.
For larger buildings, the Army Corps of Engineers has developed protection criteria that include air locks and heavy filtration systems. None of these approaches meet the needs of protecting the general population from airborne contaminants in a cost-effective manner.
Chemical, biological, or radioactive weapons are most destructive when deployed against civilian populations. When such a weapon is activated or detonated near an office, school, hospital, fire or police building, airbore agents may rapidly penetrate the building through the HVAC system doors, windows and leaks in the walls. Even if the filtration has been included on the basic HVAC system, airborne agents can penetrate the openings that are present in virtually all modern buildings.
Most residential, commercial and government buildings have not implemented measures to protect the inhabitants other than the very few people in the internal building enclosures designed with portable or built-in overpressure systems. It is also difficult or impossible to function effectively as a business or government entity if staff must remain in small protected spaces during an alert or a possible attack. In addition, buildings that have been the subject to an attack and which only provide small protected areas must be decontaminated at great expense and questionable effectiveness. Therefore, there is a need for a highly effective system that can be installed in an existing and new-build residential, commercial, or governments buildings to protect all occupants and the building interior itself from exposure to airborne agents.
A variety of devices for purifying the airflow into or out of an enclosure are available. U.S. Pat. No. 6,383,241 to Janus et al. discloses a protective filtration system for enclosures within buildings that is low-cost and portable.
U.S. Pat. No. 4,790,863 to Nobiraki et al. discloses a thin, lightweight fan module having one or more fans contained with the casing, a thin lightweight air filter module and a porous air flow modulator disposed between the fan module and the air filter module.
U.S. Pat. No. 4,905,578 to Curtis et al. discloses a portable enclosure for ventilating controlled areas that includes a blower located in an enclosure.
U.S. Pat. No. 5,462,484 to Jung et al. and U.S. Pat. No. 5,876,279 to Renz et al disclose a self-contained air cleaning system for use in a clean room.
However, none of these references provide for an air injection system which contains all of the items needed to effectively protect all the occupants from exposure to dangerous biological, radioactive, or chemical agents and which can be used cost-effectively with the current building existing HVAC system.
Accordingly, it is desirable to provide a method an apparatus that is able to filter out airborne contaminants before they are spread through an occupied building through the use of an HVAC system.